Preheat oven to 350°. Set aside 1 cup of the dry yellow cake mix and combine remaining mix with one egg and 1/2 cup softened margarine in large bowl. Press with fork into a lightly greased 9 x 13-inch pan. Mix pumpkin, 2 eggs, brown sugar, canned milk and pumpkin pie spices and pour over cake mixture: For the topping, mix cinnamon, the 1 cup reserved yellow cake mix, 1/4 cup margarine (not melted) and white sugar. Sprinkle topping over pumpkin mixture. Bake 35 to 45 minutes in middle of oven. Serve warm with whipped topping. Serves 12 to 15.